Advanced OSPF, NLSP, IS_IS and Troubleshooting.pdf

Copyright ? 1998, Cisco Systems, Inc. All rights reserved. Printed in USA. 0934_04F9_c4.scr 1 1? 1999, Cisco Systems, Inc. 316 0934_04F9_c4 2? 1999, Cisco Systems, Inc. 316 0934_04F9_c4 Advanced OSPF/NLSP/ISIS and Troubleshooting Session 316 Copyright ? 1998, Cisco Systems, Inc. All rights reserved. Printed in USA. 0934_04F9_c4.scr 2 3 316 0934_04F9_c4 ? 1999, Cisco Systems, Inc. Topics ? Review: What Is a Link State Protocol? ? Design Issues Network Cores Advanced Design Techniques Scaling an LS IGP ? Troubleshooting 4? 1999, Cisco Systems, Inc. 316 0934_04F9_c4 Link State Basics Copyright ? 1998, Cisco Systems, Inc. All rights reserved. Printed in USA. 0934_04F9_c4.scr 3 5 316 0934_04F9_c4 ? 1999, Cisco Systems, Inc. Router A’s LSDB LSP B LSP C LSP A LSP D Router B’s LSDB LSP B LSP C LSP A LSP D Router C’s LSDB LSP B LSP C LSP A LSP D Router D’s LSDB LSP B LSP C LSP A LSP D Each Router Has the Same LSDB 6 316 0934_04F9_c4 ? 1999, Cisco Systems, Inc. Properties of a Link State Protocol ? Neighbor discovery ? Constructing an LSA/LSP ? Distribute LSP/LSA ? Compute routes—SPF algorithm ? On network failure New LSPs flooded All routers recompute routing tables Copyright ? 1998, Cisco Systems, Inc. All rights reserved. Printed in USA. 0934_04F9_c4.scr 4 7 316 0934_04F9_c4 ? 1999, Cisco Systems, Inc. Scalability Issues with LS Protocols ? Limited resources CPU Memory Bandwidth ? LSP/LSA flooding High CPU—BW Fully meshed networks 8? 1999, Cisco Systems, Inc. 316 0934_04F9_c4 Link State NBMA Core Copyright ? 1998, Cisco Systems, Inc. All rights reserved. Printed in USA. 0934_04F9_c4.scr 5 9 316 0934_04F9_c4 ? 1999, Cisco Systems, Inc. Non-Broadcast Multi-Access Nets ? Examples: Frame Relay—ATM—X.25 ? Some or all routers have many neighbors ? SPF requires more resources ? Many neighbors means lots of duplicate flooding 10 316 0934_04F9_c4 ? 1999, Cisco Systems, Inc. NBMA Physical Topology Copyright ? 1998, Cisco Systems, Inc. All rights reserved. Printed in USA. 0